Gun for welding tubes on a tube plate

ABSTRACT

A rotatable welding gun comprising an electron gun, a secondary vacuum chamber around the said gun and a primary vacuum chamber at the level of the joint to be welded, a centering mandrel, a sealing plug at the free extremity of said mandrel and an annular sealing joint on the periphery of said primary vacuum chamber, in order to weld automatically the tubes of a heat exchanger on the bottom plates.

U nited btates Patent 11 1 1111 3,783,230 Peyrot Jan. 1, 1974 [54] GUNFOR WELDING TUBES ON A TUBE 3,426,173 2/1969 Steigerwald 219 121 EB3,497,666 2/1970 Hausen 219/121 EB PLATE 3,535,489 10/1970 Hlnrichs219/60 A X [76] Inventor: Jean-Pierre Peyrot, 1 place de la Division duGeneral Leclerc, Val de Marne, France Primary E.raminer-.l. V. TruheFiled: g 1972 Attorney-Karl W. Flocks [21] Appl. No.: 279,693

Related U.S. Application Data 57 ABSTRACT [63] Continuation-impart ofSer. No. 64,506, Aug. 17,

1970, aban one A rotatable welding gun comprising an electron gun, asecondary vacuum chamber around the said gun and a U.S- Cl. primaryvacuum chamber at the level of the joint to be [51 elded a enteringmandrel a ealing at th free Field of Search 219/121 EB, 121 extremity ofsaid mandrel and an annular sealing joint 219/60 A, 125, 72 on theperiphery of said primary vacuum chamber, in order to weld automaticallythe tubes of a heat ex- [56] Refer s Clled changer on the bottom plates.

UNITED STATES PATENTS 3,463,899 8/1969 Foulquier et a1. 219 121 EB 6Claims, 4 Drawing Figures GUN FOR WELDING TUBES ON A TUBE PLATEBACKGROUND OF THE INVENTION This application is a continuation-in-partof US Pat. application Ser. No. 64,506 filed Aug. 17, 1970, nowabandoned.

The present invention relates to a gun for welding tubes on a tubeplate, and more particularly to a rotary gun for welding by electronbombardment.

Welding by electron bombardment has considerable advantages, especiallyin regard to rapidity of welding and small deformationof the parts to bewelded, but the necessity of ensuring a vacuum around the weld sometimeslimits its use.

In particular, for welding a large number of exchanger tubes on the endplates, it is desirable to have available a rotary gun with electronbombardment.

SUMMARY OF THE INVENTION The present invention also provides a rotaryelectron welding gun which ensures the necessary vacuum around the weld,to the exclusion of any other device.

The invention also provides a rotary electron welding gun speciallyadapted for welding tubes on the endplate of an exchanger, the gun beingcentered on the tube by means of an expanding mandrel which terminatesin a sealing plug, a circular joint being provided around the face ofthe gun in contact with the end-plate in order to give perfectfluid-tightness.

The sealing of the tube in the plate is ensured by previously rollingover the end of the tube.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristic features andadvantages will be brought out in the description which follows belowmade with reference to the accompanying drawings, showing by way ofindication but not in any limitative sense a rotatable welding gunaccording to the invention, wherein:

FIGS. 1A and 1B together show a diagrammatic view in partial elevationalsection of the complete rotatable welding gun of the present inventionin operation position connected to the opposite positions at lines lA1Aand lB-1B respectively;

FIG. 2 is an enlarged sectioned view of the expanding mandrel portion ofthe rotatable welding gun of FIGS. lA-lB showing inner and outerportions depicted on opposite sides of the longitudinal center line;

FIG. 3 is a view of the isolating gate along line 3--3 of FIG. 18.

DESCRIPTION OF THE PREFERRED EMBODIMENT Shown in portions in FIGS. lA-1Bare a thick plate 2 having a tube 3 expanded or rolled at 4 in the plate2.

Against the plate 2 there is forced the gun 5 which is centered in theexpanded tube 3.

The gun '5 is provided with an expanding mandrel 6, also shown in theenlarged view of FIG. 2, wherein is shown separately the inner and outerportions, having accurate centering, in which are ball-bearings 7 whichenable the rotating system to operate. The rotating system compresses,fixed to each other, a shaft 8 serving as a support for the currenttransmitter of the gun 9, and a focussing coil 10, a valve support andcentering shaft 11 and a valve 12, shown in another view of FIG.

3, which enables the system to be accurately centered on the axis of thetube 3 during the rotational movement of the system moved by means of amotor 13.

This rotating system is centered and can rotate inside the fixed body ofthe gun on ball-bearings 16 and 17 and other positioned bearings shown.

The support 11 is pierced with a hole 19 permitting the passage of theelectron beam. This orifice 19 is closed by means of a fixed jack 21acting on the slidevalve 12 when this slide value 12 is in front of jack21. The tightness of the sealing between chambers in part 35 and chamber28 is formed by the slide-valve 12 against joint 20. This flatseparating sliding type valve enables the gun to be kept under asecondary vacuum in the upper chamber, when the lower chamber comprisingthe joint to be welded is put into communication with free air. Duringrotation the valve 12 is always kept opened by spring 23. Electricalsafety devices are provided for preventing the closing action of thejack 21 when the gun 5 is not in the starting position. Sliding valve 12is thus normally biased by spring 23 and, in the open position of thevalve, the hole 50 is aligned with orifice 19 of support 11 of slidingvalve 12. The closing jack 21 is provided to, in a determinate fixedconvenient position of the rotating gun (FIG. 18), to close the valve 12in the direction of arrow F2 (FIG. 3) and, in that case, the hole 50 ofvalve 12 is moved downwardly radially outside of the axis of theelection gun, and all communication is closed between primary chamber 35and secondary chamber 28. Consequently while valve 12 rotates with themovable parts of gun 5 communication between chambers is maintained openfor passage of the electron beam.

The coil 10 is rigidly connected for rotation with the gun 9, thecathode of which can rapidly be taken down, following applicants U. S.Pat. No. 3,612,942 dated Oct. 12,1971.

The gun 9 is fixed and centered with respect to the axis of rotation onthe plate-shaft 8 by a readily removable quick-grip plug-in device. Theshaft 8 may also serve as a current transmitter using a mercury bath,the whole forming the fluid-tight rotating mercury seal known per se.The current supply leads are shown at 25 which are fed through theelectric power supply cable 14.

The motor 13 and the reduction gearing 27 are rigidly fixed to the fixedbody of the overall welding gun and coupling shown ensures theconnection of shaft 8 to motor 13 through reduction gearing 27.

The fixed body constitutes the shell of the vacuum chambers 28. Thesecondary vacuum chamber in which the electron gun 9 is located is keptfluid-tight by means of the joints 29 and 30. Pumping is effectedthrough the orifice 31. In order to create the vacuum, a flexible pipe26 couples a secondary pump to metal part 32, the fluid-tightness ofthis part around the orifice 31 being effected by a joint 33.

The primary vacuum chamber is formed by a metal part 35. Itsfluid-tightness is ensured by the joints 37 and 38 and the expandedportion 4. In order to create the vacuum, a flexible pipe 15 joins theprimary pumping branch circuit of the secondary pump to the orifice 39.

As shown in the enlarged view of FIG. 2 the expanding mandrel 6 has ballbearings 7 forced outward against tube 3 through action of springs 41causing sliding parts 43 to cam bearings 42 against a sloping surface ofsliding parts 43. This maintains an outward force from mandrel 6 againsttube 3 to give the mandrel its expanding action. The ball bearings 7 onthe inner portion of mandrel 6 supports shaft 44 forming the center ofmandrel 6 which rotates through its connection to the rotating systemand its ultimate connection to shaft 8.

It can be seen that the rotatable gun according to the invention permitsaccurate welding by electron bombardment of tubes expanded into a plate,in a very rapid manner, since it is only necessary to create the primaryvacuum in a very small chamber in a few seconds, to open an extra-flatvalve in a few seconds and to carry out the welding in a few seconds.

It will of course be understood that the present invention has beendescribed above purely by way of indication of a preferred example andnot in any limitative sense, and that any equivalence may be introducedinto its constituent elements without thereby departing from its scope,as defined by the appended claims.

What is claimed is:

l. A rotatable portable welding gun for welding a tube extending from aplate at a joint to said plate comprising an electron gun,

means to rotate said electron gun connected to said electron gun,

a secondary vacuum chamber around said electron a primary vacuum chamberat a level of a joint to be welded having an opening over the tube to bewelded,

a centering mandrel extending from and aligned with an opening in saidprimary vacuum chamber,

a sealing joint on said mandrel and an annular sealing joint on theperiphery of the opening in said primary vacuum chamber,

value means connecting said vacuum chambers, said vacuum chamberssubstantially coaxial with said centering mandrel and located togetherwith said rotating means and said sealing joints on the opposite end ofsaid mandrel from its free end. 2. A welding gun in accordance withclaim 1 further characterized by said electron gun being displacedradially with respect to the axis of said mandrel and connected torotate about the center axis of said mandrel. 3. A welding gun inaccordance with claim 1 further characterized by said value meanscomprising a flat isolation valve for said secondary vacuum chamber,located between said secondary and primary vacuum chambers, said valvealways being in an open position during rotation of said electron gun.4. A welding gun in accordance with claim 3 further characterized bysaid isolation valve including a slide, a jack attached to said slide,means to push against said jack in contact with said jack at least aportion of the time during rotation of said electron gun, spring meansto oppose said pushing means. 5. A welding gun in accordance with claim4 further characterized by a support means for said slide and said jackhaving a hole therethrough aligned with the beam of said electron gun toallow passage of said beam. 6. A welding gun in accordance with claim 7further characterized by said valve closing said hole only at adetermined radial starting position of the rotating of said electrongun.

1. A rotatable portable welding gun for welding a tube extending from aplate at a joint to said plate comprising an electron gun, means torotate said electron gun connected to said electron gun, a secondaryvacuum chamber around said electron gun, a primary vacuum chamber at alevel of a joint to be welded having an opening over the tube to bewelded, a centering mandrel extending from and aligned with an openingin said primary vacuum chamber, a sealing joint on said mandrel and anannular sealing joint on the periphery of the opening in said primaryvacuum chamber, value means connecting said vacuum chambers, said vacuumchambers substantially coaxial with said centering mandrel and locatedtogether with said rotating means and said sealing joints on theopposite end of said mandrel from its free end.
 2. A welding gun inaccordance with claim 1 further characterized by said electron gun beingdisplaced radially with respect to the axis of said mandrel andconnected to rotate about the center axis of said mandrel.
 3. A weldinggun in accordance with claim 1 further characterized by said value meanscomprising a flat isolation valve for said secondary vacuum chamber,located between said secondary and primary vacuum chambers, said valvealways being in an open position during rotation of said electron gun.4. A welding gun in accordance with claim 3 further characterized bysaid isolation valve including a slide, a jack attached to said slide,means to push against said jack in contact with said jack at least aportion of the time during rotation of said electron gun, spring meansto oppose said pushing means.
 5. A welding gun in accordance with claim4 further characterized by a support means for said slide and said jackhaving a hole therethrough aligned with the beam of said electron gun toallow passage of said beam.
 6. A welding gun in accordance with claim 7further characterized by said valve closing said hole only at adetermined radial starting position of the rotating of said electrongun.